Results
Showing the example values — change any input to recalculate.
6/12roof pitch · 26.57°
- Angle
- 26.57°
- Slope (grade)
- 50%
- Pitch multiplier
- 1.1180
- Hip/valley factor
- 1.5000
- Category
- Conventional
- Rafter length
- 17′ 9⅞″
- Ridge height
- 7′ 6″
- Roof area
- 1,503 sq ft
- Squares
- 15.03
- Squares + waste
- 16.53
- Shingle bundles
- 50
Roofing materials allowed at 6/12
| Material | IRC minimum | At this pitch |
|---|---|---|
| Asphalt shingles | 2/12 | OK |
| Clay or concrete tile | 2½/12 | OK |
| Metal shingles | 3/12 | OK |
| Wood shingles / shakes | 3/12 | OK |
| Slate | 4/12 | OK |
| Mineral-surfaced roll roofing | 1/12 | OK |
| Standing-seam metal panels | ¼/12 | OK |
Show the math (13 steps)
- Rise ÷ run = 0.50006 ÷ 12
- Pitch (rise per 12 of run) = 6/120.5000 × 12
- Angle = 26.57°atan(0.5000)
- Slope (grade) = 50%0.5000 × 100
- Pitch multiplier = 1.1180√(1 + 0.5000²)
- Hip/valley factor = 1.5000√(6² + 16.97²) ÷ 12
- Ridge height above wall plate = 7.50 ft(30 ÷ 2) × 0.5000
- Common rafter length = 17.82 ft(15 − 0.75″ ridge + 12″ overhang) × 1.1180
- Plan (footprint) area incl. overhang = 1,344 sq ft(30 + 2 × 1) × (40 + 2 × 1)
- Roof surface area = 1,502.6 sq ft1,344 × 1.1180
- Roofing squares = 15.031,502.6 ÷ 100
- Squares + 10% waste = 16.5315.03 × 1.1
- Shingle bundles (3 per square) = 50⌈16.53 × 3⌉